Biomedical subjects

Michael J Owens

Publications and source records attributed to Michael J Owens.

At least 19 recordsLinked to original sources

PubMed2007

Preparation of antidepressants for use in preclinical research.

Obtaining drugs for use in basic and preclinical research has become increasingly difficult and in many instances is dependent upon the company's interest in the proposed research. In this paper, we describe a simple procedure for extracting the antidepressants sertraline, paroxetine, fluoxetine, venlafaxine, citalopram, escitalopram, duloxetine and atomoxetine from their readily available pharmaceutical preparations. With the exception of citalopram, escitalopram and duloxetine in which the free base was the final product, the hydrochloride salt forms of these drugs were prepared. This procedure provides these antidepressants in gram quantities in recovered yields ranging from 53% to 100% at over 99% purity and is in principle applicable to other drugs as well.

Antidepressive Agents↗

PubMed2006

Synthesis, radiosynthesis, and biological evaluation of carbon-11 labeled 2beta-carbomethoxy-3beta-(3'-((Z)-2-haloethenyl)phenyl)nortropanes: candidate radioligands for in vivo imaging of the serotonin transporter with positron emission tomography.

2beta-carbomethoxy-3beta-(3'-((Z)-2-iodoethenyl)phenyl)nortropane (mZIENT, 1) and 2beta-carbomethoxy-3beta-(3'-((Z)-2-bromoethenyl)phenyl)nortropane (mZBrENT, 2) were synthesized and evaluated for binding to the human serotonin, dopamine, and norepinephrine transporters (SERT, DAT, and NET, respectively) using transfected cells. Both 1 and 2 have a high affinity for the SERT (Ki=0.2 nM) and are approximately 160 times more selective for the SERT than the DAT. Compound 2 has a significantly higher affinity for the NET than 1, and this may be a result of the different size and electronegativity of the halogen atoms. MicroPET imaging in nonhuman primates with [11C]1 and [11C]2 demonstrated that both tracers behave similarly in vivo with high uptake being observed in the SERT-rich brain regions and peak uptake being achieved in about 55 min postinjection. Chase studies with citalopram and methylphenidate demonstrated that this uptake is the result of preferential binding to the SERT.

Animals↗

PubMed2006

Synthesis and monoamine transporter affinity of front bridged tricyclic 3beta-(4'-halo or 4'-methyl)phenyltropanes bearing methylene or carbomethoxymethylene on the bridge to the 2beta-position.

A series of front bridged tricyclic 3beta-(4'-halo or 4'-methyl)phenyltropanes bearing methylene or carbomethoxymethylene on the bridge to the 2beta-position was synthesized, and their binding affinities were determined in cells transfected to express human norepinephrine transporter (NET), serotonin transporter (SERT), and dopamine transporter (DAT) via competition binding assays. All compounds studied in this series exhibit a moderate to high potency at all three transporters with SERT or DAT selectivity. 3beta-(4'-iodo)phenyltropane bearing methylene on the bridge to the 2beta-position (24) presents a particularly attractive pharmacological profile, with very high SERT affinity (K(i) = 0.09 nM) and selectivity versus NET (65-fold) and DAT (94-fold).

Animals↗

PubMed2006

Algorithmically designed peptides ameliorate behavioral defects in animal model of ADHD by an allosteric mechanism.

This study exemplifies the use of three ADHD-relevant methodological innovations. (1) The use of novel, patented, computational peptide design techniques to generate peptides targeting the extra-cellular and para-transmembrane amino acid loops of the putatively ADHD-involved, D(2) dopamine receptor, D(2)DAR; (2) experimental evidence that these peptides in L-amino acid/ortho ordered or D-amino acid/reverse ordered (retro-inverso), D(2)DAR, hydrophobic eigenmode matched forms, evoked positive allosteric and indirect agonist influences on in vitro stably receptor transfected CHO and LtK cells and on in vivo, brain mediated activity; (3) a representative 15 residue all-D-amino acid, D(2) mode matched peptide, given parenterally, was found to "repair" a key aberrant ADHD behavioral characteristic in a standard animal model of ADHD, the Spontaneously Hypertensive Rat, SHR, relative to its progenitor species control, the Wistar-Kyoto rat, WKY. The representative, retro-inverso peptide, all-D-LLYKNKPRYPKRNRE, reversed SHR's relative deficiency in sensory motor gating (pre-pulse inhibition, PPI) while leaving SHR's nonselective attention (rearings), impulsive behavior (time in center), and activity level (timed total motor behavior) unchanged. Amphetamine also reversed SHRs sensory gating defect, but with significant increases in nonselective attention, impulsivity and hyperactivity. These preliminary results suggest the possibility of a new, "softer" pharmacological approach to ADHD: hydrophobic mode matched peptide allosteric augmentation of the activity of indigenous dopamine with respect to D(2)DAR mediated function, in place of stimulant drug-induced presynaptic dopamine release or impairment of dopamine uptake.

Acoustic Stimulation↗

PubMed2006

Elevated cerebrospinal fluid substance p concentrations in posttraumatic stress disorder and major depression.

OBJECTIVE: The authors tested the hypothesis that concentrations of the pain-transmitting neuropeptide substance P are elevated in the CSF of patients with major depression or posttraumatic stress disorder (PTSD), which have overlapping symptoms. The authors also sought to determine if CNS substance P concentrations change on provocation of symptoms in PTSD patients. METHOD: The authors measured CSF substance P concentrations in medication-free patients with either major depression or PTSD and in healthy comparison subjects. Next, using a within-subject, crossover design, the authors sampled CSF for 6 hours through an indwelling subarachnoid catheter in PTSD patients before, during, and after exposure to a 60-minute traumatic or neutral videotape stimulus. RESULTS: Both depressed and PTSD patients had significantly elevated basal CSF substance P concentrations. In the challenge study, marked increases in CSF substance P concentrations were found only after precipitation of PTSD symptoms. CSF substance P concentrations increased by 169% and 90.6% of baseline levels at 10 and 70 minutes, respectively, after the start of the traumatic videotape but changed by only 1.1% and -8.1% of baseline levels 10 and 70 minutes after the start of the neutral videotape. CONCLUSIONS: These results suggest that elevated CNS substance P concentrations are involved in both major depression and PTSD. The marked increase in CSF substance P concentrations during and after the symptom-provoking stimulus, but not after the neutral stimulus, implicates CNS release of substance P in the mechanism of acute PTSD symptoms. These data also reveal that CNS substance P responds acutely to psychological stress in humans.

Acute Disease↗

PubMed2006

Antidepressants in amniotic fluid: another route of fetal exposure.

OBJECTIVE: The authors' goal was to determine the concentration of antidepressants in amniotic fluid during maternal treatment of depression. METHOD: Women treated with antidepressants undergoing amniocentesis for obstetrical reasons were enrolled. Antidepressant concentrations in amniotic fluid and maternal serum were determined with high-performance liquid chromatography. RESULTS: Amniotic fluid was obtained from 27 women, and the amniotic fluid's antidepressant concentrations were highly variable. For the parent compounds, the amniotic fluid concentrations of selective serotonin uptake inhibitors averaged 11.6% (SD=9.9%) of maternal serum concentrations (N=22). Amniotic fluid to maternal serum ratios were higher for venlafaxine: 172% (SD=91%) (N=3). Of interest, the amniotic fluid to maternal serum ratios for the metabolites (N=19) did not demonstrate a consistent pattern compared to the parent compound ratios. In 10 subjects, the amniotic fluid to maternal serum ratio for the metabolites was higher than the parent compound and lower in the remaining nine subjects. CONCLUSIONS: The pattern of antidepressant concentrations in amniotic fluid is similar to recent data for placental passage. Although the significance of amniotic fluid exposure remains to be determined, these results demonstrate that maternally administered antidepressants are accessible to the fetus in a manner not previously appreciated.

Amniocentesis↗

PubMed2006

Therapeutic drug monitoring of psychoactive drugs during pregnancy in the genomic era: challenges and opportunities.

Various symptoms of mental illness occur commonly during pregnancy. It is estimated that serious mental disorders, including major depression, bipolar disorder, schizophrenia, panic and other anxiety disorders, occur with a frequency of 10 to 25% in community samples of US women in their child-bearing years. As a result, approximately a third of all women take at least one psychoactive drug during pregnancy. Fetal drug exposure has been documented for all psychoactive drugs studied to date. However, the rate and extent of placental transfer within and between psychoactive drug classes remains ill defined. The contribution of various genetic factors such as the role of polymorphic drug metabolizing enzymes and drug transporters in controlling the variability of fetal drug exposure is also unclear. Therapeutic drug monitoring (TDM) has traditionally played an important role in psychiatric pharmacotherapy during pregnancy to ensure an adequate drug dose to achieve desired benefits while avoiding excessive fetal accumulation for drugs. In the genomic era, individualized treatment with specific drugs tailored to the mother's and fetus's genotype should eventually become the standard of care. Several methodological problems need to be overcome for this prediction to become reality. One approach to this goal taken by the Specialized Center of Research on Sex and Gender Factors Affecting Women's Health at the Emory University Women's Mental Health Program is described. This research is grounded on TDM of pregnant women receiving antidepressants, antipsychotics, anti-epileptic drugs and mood stabilizers. The use of pharmacokinetic and pharmacogenetic models to predict maternal plasma drug concentrations, fetal drug exposure, and maternal and neonatal outcomes, is expected to improve our understanding of dose-response relationships of psychoactive drugs in pregnancy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2006

Maternal-infant response to variable foraging demand in nonhuman primates: effects of timing of stressor on cerebrospinal fluid corticotropin-releasing factor and circulating glucocorticoid concentrations.

The maternal stress response may vary as a function of infant developmental phase. Using a median split, 13 bonnet macaque (M. radiata) mother-infant dyads were exposed to early initiation of variable foraging demand (VFD), a prolonged stressor, whereas 11 dyads were exposed to late VFD onset. Cerebrospinal fluid (CSF) and plasma samples were obtained from mothers and infants prior to and following VFD. Increases in maternal CSF corticotropin-releasing factor (CRF) concentrations were evident in response to late, but not early, VFD. Mothers exhibited either increased or decreased cortisol concentrations in response to VFD. However, absolute cortisol change was greater in early versus late VFD. Timing of the VFD stressor differentially affects maternal neuroendocrine response, with potential implications for the offspring's developmental trajectory.

Agonistic Behavior↗

PubMed2006

Serotonin and norepinephrine transporter binding profile of SSRIs.

Even today, pharmacotherapy for mood disorders is based almost entirely on the observation in the 1950s and 1960s that agents that enhance monoamine transmitter activity are effective antidepressants. Preclinical studies have shown that long-term administration of nearly all effective antidepressants increases the efficiency of postsynaptic serotonin transmission; many also modify central noradrenergic activity. For the majority of antidepressants, these changes are the result of their ability to block serotonin and/or norepinephrine activity at their "presynaptic uptake sites" (i.e., at the serotonin transporter [SERT] or the norepinephrine transporter [NET]). Drugs that are highly selective for one transporter over another have been demonstrated to be effective and tolerable, whereas agents that act on multiple transporters may not necessarily achieve better efficacy and may result in additional adverse events. The rationale for the use of drugs that affect multiple transports is based on the suggestion that antidepressants that block both the SERT and the NET may provide better efficacy. This can only be determined through empirical studies.

Animals↗

PubMed2005

Virally mediated increased neurotensin 1 receptor in the nucleus accumbens decreases behavioral effects of mesolimbic system activation.

Dopamine receptor agonist and NMDA receptor antagonist activation of the mesolimbic dopamine system increases locomotion and disrupts prepulse inhibition of the acoustic startle response (PPI), paradigms frequently used to study both the pharmacology of antipsychotic drugs and drugs of abuse. In rats, virally mediated overexpression of the neurotensin 1 (NT1) receptor in the nucleus accumbens antagonized d-amphetamine- and dizocilpine-induced PPI disruption, hyperlocomotion, and D-amphetamine-induced rearing. The NT receptor antagonist SR 142948A [2-[[5-(2,6-dimethoxyphenyl)-1-(4-N-(3-dimethylaminopropyl)-N-methylcarbamoyl)-2-isopropylphenyl)-1H-pyrazole-3-carbonyl]amino] adamantane-2-carboxylic acid, hydrochloride] blocked inhibition of dizocilpine-induced hyperlocomotion mediated by overexpression of the NT1 receptor. Together, these results suggest that increased nucleus accumbens NT neurotransmission, via the NT1 receptor, can decrease the effects of activation of the mesolimbic dopamine system and disruption of the glutamatergic input from limbic cortices, resembling the action of the atypical antipsychotic drug clozapine. In contrast to clozapine, virally mediated overexpression of the NT1 receptor in the nucleus accumbens had prolonged protective effects (up to 4 weeks after viral injection) without perturbing baseline PPI and locomotor behaviors. These data further confirm the NT1 receptor as the receptor mediating the antistimulant- and antipsychotic-like properties of NT and provide rationale for the development of NT1 receptor agonists as novel antipsychotic drugs. In addition, the NT1 receptor vector might be a valuable tool for understanding the mechanism of action of antipsychotic drugs and drugs of abuse and may have potential therapeutic applications.

Animals↗

PubMed2005

The electrophysiological effects of neurotensin on spontaneously active neurons in the nucleus accumbens: an in vivo study.

Considerable evidence obtained from neuroanatomical and neurochemical studies suggests an interaction between the endogenous tridecapeptide neurotensin (NT) and central nervous system dopamine (DA) neurons. Centrally administered NT blocks many of the actions of synaptic DA in limbic brain areas; the specific mechanism and receptors involved remain under investigation. The electrophysiological effects of NT were studied using extracellular recording techniques and iontophoretic application in 243 spontaneously active neurons in the nucleus accumbens (NAc), with a positive/negative waveform. NT was directly applied to 208 neurons in a pulsatile fashion by iontophoresis (21+/-1 nA). NT had no effect on the firing rate of 120 neurons ((0.31+/-0.72)%), decreased the firing rate in 51 neurons ((-27.87+/-1.52)%), and increased the firing rates of 37 neurons ((33.38+/-2.6)%). One hundred ninety nine (81.9%) of the neurons studied were sensitive to iontophoretically applied DA (>15% decrease in firing rate). The effects of continuous NT application on DA-induced inhibitions were studied in 169 neurons. NT attenuated neuronal responses to directly applied DA by (49.95+/-4.52)%, with antagonism in the "core" subregion (n=96) of (33.41+/-7.75)% when compared with antagonism in the "shell" subregion (n=71) of (61.39+/-5.2)%. The effects of NT on DA were consistent and independent of the effects of NT alone. These data provide further evidence that NT functions as a true neuromodulator in the NAc, exerting minimal direct effects, but blocking the actions of DA.

Action Potentials↗

PubMed2005

The variable number of tandem repeats element in DAT1 regulates in vitro dopamine transporter density.

BACKGROUND: A 40-bp variable number of tandem repeats (VNTR) polymorphism exists in the 15th exon of DAT1, the gene encoding the human dopamine transporter (DAT). Though the VNTR resides in a region encoding the 3' untranslated region (UTR) and does not alter the protein's amino acid sequence, the prevalent 10-repeat variant has shown both linkage and association to Attention Deficit Hyperactivity Disorder (ADHD). In this study, we examined the effects of the DAT1 VNTR on measures of in vitro DAT expression and pharmacology. A series of four DAT1 constructs, each containing the DAT1 coding region, but varying with respect to the downstream presence or content of the 3'UTR, were engineered and stably transfected into an HEK-293 variant using Flp-In integration, an enzyme-mediated, site-specific recombination technology. RESULTS: [3H] Win 35,428 saturation binding assays and DAT immunoblots revealed statistically significant differences in DAT expression attributable to DAT1 genotype. Cells harboring the 10-repeat DAT1 variant were characterized by a Bmax approximately 50% greater than cells with the 9-repeat VNTR; those containing only the DAT1 coding region or the coding region flanked by a truncated 3' UTR resulted in greater DAT density than either of the naturalistic 9- and 10-repeat variants. Competition binding assays showed no statistically significant DAT1 genotype effects on the DAT affinity for methylphenidate, a finding consistent with the positional location of the VNTR. CONCLUSION: This study identified the DAT1 VNTR as a functional polymorphism and provides an interpretive framework for its association with behavioral phenotypes.

Attention Deficit Disorder with Hyperactivity↗

PubMed2005

Placental passage of tricyclic antidepressants.

BACKGROUND: The use of antidepressants during pregnancy continues to garner considerable attention, though there are limited investigations that have sought to quantify fetal exposure. METHODS: Maternal and umbilical cord sera were collected at delivery from ten women taking nortriptyline and seven taking clomipramine. Placental passage was calculated as the ratio of umbilical cord to maternal serum concentration. Obstetrical outcome data were gathered from subjects at delivery. RESULTS: The placental passage ratio of nortriptyline and its active metabolite, cis-10-hydroxynortriptyline, were .68 +/- .40, 1.40 +/- 2.40, respectively. Clomipramine and desmethylclomipramine ratios were .60 +/- .50, .80 +/- .60. Obstetrical complications, such as pre-term delivery and pregnancy induced hypertension, were increased compared to the national average. CONCLUSIONS: The in vivo ratios of umbilical cord to maternal serum drug concentrations demonstrate considerable fetal exposure and differ greatly from previous results utilizing ex vivo perfusion.

Antidepressive Agents, Tricyclic↗

PubMed2005

Genetic analysis of the hypothalamic corticotropin-releasing factor system.

The goal of this study was to use BxD recombinant inbred mice to search for genes that control the hypothalamic corticotrophin-releasing factor (CRF) system. The specific phenotype that was measured was abundance of transcripts that encode CRF, CRF receptor (Crf-R1), CRF binding protein, and arginine vasopressin (AVP) in total hypothalamic RNA. The strain distribution patterns for the transcript abundances for each target were continuously distributed, consistent with these being quantitative traits. Marker regression and interval mapping revealed associations with quantitative trait loci (QTL) for CRF transcript abundance on chromosome 1 (at 89.2 cM), chromosome 12 (between 54-58 cM), and chromosome 13 (between 26-30 cM); for Crf-R1 transcript abundance on chromosome 7 (at 1.5 cM), chromosome 12 (at 37 cM), and chromosome X (at 30 cM); for CRF binding protein transcript abundance on chromosome 7 (at 48.5 cM), chromosome 8 (at 65 cM), and chromosome 12 (at 19 cM); and for AVP transcript abundance on chromosome 7 (at 1 cM), chromosome 12 (at 13 cM), and chromosome 13 (at 45 cM). The transcript abundance QTL were not linked to their respective structural genes. Interval mapping on chromosome 7 reveals substantial overlap between QTL that control AVP and Crf-R1 transcript abundance and on chromosome 12 for QTL that control CRF and Crf-R1, which may indicate loci that coordinate regulation of the CRF system. There are QTL for all four targets on chromosome 12. There are a number of neurodevelopmental genes in very close proximity to the transcript abundance QTL that are potential candidate genes.

Animals↗

PubMed2005

Carbon-11 HOMADAM: a novel PET radiotracer for imaging serotonin transporters.

UNLABELLED: Carbon-11-labeled N,N-dimethyl-2-(2'-amino-4'-hydroxymethylphenylthio)benzylamine (HOMADAM) was synthesized as a new serotonin transporter (SERT) imaging agent. METHODS: Carbon-11 was introduced into HOMADAM by preparation of N-methyl-2-(2'-amino-4'-hydroxymethylphenylthio)benzylamine followed by alkylation with carbon-11 iodomethane. Binding affinities of HOMADAM and the radiolabeling substrate, N-methyl-2-(2'-amino-4'-hydroxymethylphenylthio)benzylamine, were determined in cDNA transfected cells expressing human SERT, dopamine transporters (DAT) and norepinephrine transporters NET using [3H]citalopram, [(125)I]RTI-55 and [3H]nisoxetine, respectively. MicroPET brain imaging was performed in monkeys. Arterial plasma metabolites of HOMADAM were analyzed in a rhesus monkey by high-performance liquid chromatography (HPLC). RESULTS: HOMADAM displayed high affinity for the SERT (Ki = 0.6 nM). N-methyl-2-(2'-amino-4'-hydroxymethylphenylthio)benzylamine displayed moderate affinity for the SERT (Ki = 15.11 nM). The affinities of HOMADAM for the DAT and NET were 2000- and 253-fold lower, respectively, than for the SERT. [11C]HOMADAM was prepared from [11C]iodomethane in approximately 25% radiochemical yield (decay-corrected to end of bombardment). MicroPET brain imaging studies in monkeys demonstrated that [11C]HOMADAM uptake was selectively localized in the midbrain, thalamus, pons, caudate, putamen and medulla. The midbrain-to-cerebellum, pons-to-cerebellum, thalamus-to-cerebellum and putamen-to-cerebellum ratios at 85 min were 4.2, 2.8, 2.3 and 2.0, respectively. HOMADAM binding achieved quasi-equilibrium at 45 min. Radioactivity in the SERT-rich regions of monkey brain was displaceable with R,S-citalopram. Radioactivity in the DAT-rich regions of monkey brain was not displaceable with the DAT ligand RTI-113. Radioactivity in the SERT-rich regions of monkey brain was displaceable with the R,S-reboxetine, a NET ligand with a high nanomolar affinity for SERT. Arterial plasma metabolites of HOMADAM were analyzed in a rhesus monkey by HPLC and displayed a single peak that corresponded to unmetabolized HOMADAM. CONCLUSION: HOMADAM is an excellent candidate for PET primate imaging of brain SERTs.

Animals↗

PubMed2005

Synthesis and biological evaluation of trans-3-phenyl-1-indanamines as potential norepinephrine transporter imaging agents.

The development of radioligands suitable for studying the central nervous system (CNS) norepinephrine transporter (NET) in vivo will provide important new tools for examining the pathophysiology and pharmacotherapy of a variety of neuropsychiatric disorders including major depression. Towards this end, a series of trans-3-phenyl-1-indanamine derivatives were prepared and evaluated in vitro. The biological properties of the most promising compound, [(11)C]3-BrPA, were investigated in rat biodistribution and nonhuman primate PET studies. Despite high in vitro affinity for the human NET, the uptake of [(11)C]3-BrPA in the brain and the heart was not displaceable with pharmacological doses of NET antagonists.

Animals↗

PubMed2005

Synchronized maternal-infant elevations of primate CSF CRF concentrations in response to variable foraging demand.

BACKGROUND: The study of environment-gene interactions during neurodevelopment may facilitate our understanding of the origins of psychiatric disorders. Environmental contribution to the neurobiology of psychopathology is perhaps most relevant during infancy, where vulnerability to early-life stressors is particularly evident. OBJECTIVES: In the current study, we wished to examine if central corticotropin-releasing factor (CRF) would provide a plausible biological vehicle for synchronized increases in mothers and their infant. METHODS: Twenty-four mother-infant bonnet macaques (Macaca radiata) dyads, of known age and weight served as subjects. The subjects were group-housed in four pens of 5-7 dyads each, stabilized for several weeks prior to the study period. Although adequate food was always available, mothers faced uncertainty of food availability for 16 weeks within the first year of infant life, through a procedure dubbed "variable foraging demand" (VFD). Pre- and post-VFD cerebrospinal fluid (CSF) samples were obtained simultaneously on mothers and infants. RESULTS: Maternal CSF CRF concentrations exhibited a significant mean elevation of 26% from pre-VFD to post-VFD; there was no effect of number of days postpartum on maternal pre-VFD CSF CRF levels. There was a significant mean increase (45%) in infant CSF CRF concentrations over the 16-week period of the VFD paradigm. No infant sex differences were evident. Post-VFD minus pre-VFD differences in infant CSF CRF concentrations were positively correlated (r = .52; N = 16; P = .0384) with the magnitude of maternal CRF response to VFD, providing evidence of synchronized CSF CRF expression by the dyad. CONCLUSION: This parallel response within the dyad suggests, as one testable hypothesis, that maternal responsivity to the stress of the VFD condition is "communicated" between mother and infant via a CRF-mediated mechanism. The VFD stressor produces a parallel activation of the central CRF system in both mothers and their infants.

Animals↗

PubMed2004

Spontaneous withdrawal from the triazolobenzodiazepine alprazolam increases cortical corticotropin-releasing factor mRNA expression.

Corticotropin-releasing factor (CRF) is the major physiologic regulator of the hypothalamic-pituitary-adrenal (HPA) axis and plays a key role in coordinating the mammalian stress response. Substantial data implicates hyperactivity of CRF neuronal systems in the pathophysiology of depression and anxiety disorders. Enhanced CRF expression, release, and function have also been demonstrated during acute withdrawal from several drugs of abuse. Previous studies revealed that chronic administration of the anxiolytic alprazolam reduced indices of CRF and CRF1 receptor function. Conversely, measures of urocortin I and CRF2 receptor function were increased. To further scrutinize these findings, we sought to determine whether CRF neuronal systems are activated during spontaneous withdrawal from the triazolobenzodiazepine alprazolam in dependent rats and to characterize the time course, extent, and regional specificity of the patterns of activation. After 14 d of alprazolam administration (90 mg x kg(-1) x d(-1)), spontaneous withdrawal produced activation of the HPA axis, as well as suppression of food intake and weight loss that peaked 24-48 hr after withdrawal. Remarkably, CRF mRNA expression in the cerebral cortex was markedly (>300%) increased over the same time period. Other indices of CRF-CRF1 and urocortin I-CRF2A function, altered by chronic alprazolam treatment as previously described, returned to pretreatment levels over 96 hr. The physiologic significance of this dramatic induction of cortical CRF mRNA expression, as well as whether this occurs during withdrawal from other drugs of abuse is yet to be determined. The marked increase in CRFergic neurotransmission is hypothesized to play a major role in benzodiazepine withdrawal.

Adrenocorticotropic Hormone↗